Hey Guys,

I’ve recently been playing around with Elixir (and Phoenix) for a personal project it has been a pleasant experience so far. However, there’s something that’s been nagging at the back of my mind regarding how “enterprise” Elixir systems should be architected.

A bit of background - professionally I work for a small product team building and supporting an internal platform (can’t say much more than that, unfortunately) which is made up of microservices written primarily in Go which communicate using gRPC and are deployed to Kubernetes. Overall, this works exceptionally well. gRPC and Protobufs make it easy to talk to different services in a way that feels “native” with relatively low overhead. Kubernetes and Linkerd make auto-scaling and load balancing work without me having to think about much and I can spin up a new service and have it deployed in a matter of minutes.

From what I have read about Elixir and more so the Erlang VM, software that runs on the BEAM is not too dissimilar to what I just described. You can have many different applications running inside the runtime at once (à la Microservices) and the BEAM handles orchestrating these applications (à la Kubernetes). But where my confusion comes in is when you progress from something like a CRUD application to something more complex.

As an example (hypothetical) if I wanted to build some sort of real-estate analysis application at a high level it might involve the following “services”:

• Broadway to ingest data from various real-estate data providers.

• NX/Torchx for doing some sort of analysis on the ingested data.

• Oban for background tasks, like downloading images of listing and persisting them to S3 or sending scheduled property update emails to users.

• Phoenix for the web frontend to view the analysed data.

What is considered the best practice for architecting something like this? From what I have managed to gather these are the two ways that seem most intuitive to me:

• Creating an umbrella project to keep all the services together in a mono-repo but with some level of separation (however, I have seen that some people seem hesitant to recommend using umbrella projects). Coupling this with something like libcluster and/or Horde means it could easily be deployed to something like fly.io and would have good utilization of the underlying hardware.
• Create a project per “service” and have them communicate via some sort of API (I see there is a gRPC package for Elixir, tho it doesn’t seem production ready so I guess this is not a common way of doing things). The downside here is we now have network latency between service calls and would have worse utilization of the underlying hardware if using something like fly.io

Sorry if this was a bit of an essay, but would appreciate any advice and if there are any good resources for me to read on the topic that would be great too!